2025/05/26 by Guo, Mingyue, Shi, Zhenhua
#FOS: Physical sciences #Mathematical Physics (math-ph)
paper · doi:10.48550/arxiv.2505.19728
In this paper, we study the problem of local isometric immersion of pseudospherical surfaces determined by the solutions of a class of third order nonlinear partial differential equations with the type ut - uxxt = λu2 uxxx + G(u, ux, uxx),(λ∈ℝ). We prove that there is only two subclasses of equations admitting a local isometric immersion into the three dimensional Euclidean space 𝔼3 for which the coefficients of the second fundamental form depend on a jet of finite order of u, and furthermore, these coefficients are universal, namely, they are functions of x and t, independent of u. Finally, we show that the generalized Camassa-Holm equation describing pseudospherical surfaces has a universal second fundamental form.